I've tried multiple ad blockers to remove all the annoying ads in Yahoo Mail, and this is the only one that removes all of them. And every time Yahoo makes a change that causes the ads to reappear, the Developer quickly issues an update to the extension that removes the ads again. And he's very responsive to questions and comments!
And the Chrome version works as well.

在国内能下载诶

It was fine but now Yahoo is showing banner ads when you open certain emails. They want us to use Yahoo Mail Plus at $5 per month to get rid of them.. Please see if this can be fixed

супер! работает отлично

Very useful addon

It's working with blocking ads on Yahoo Mail now. Jason has fixed it for Yahoo Mail. Thank you Jason. Really appreciate it!

Used to be great, but it has now stopped working. Viewable area is no longer expanded to the right hand side.

Unfortunately, no longer works for Yahoo mail

At the time of this writing, the extension works perfectly for Outlook and does not work with Yahoo. It would also be nice if this was implemented for AOL since it is effectively the same as Yahoo. I would advise caution with any extension that can access what may be sensitive data depending upon your usage. Thanks to the developer.